Skip to content

Vitamin B12 (Serum) with Immunoassay Confirmation

Published: August 9, 2026Updated: August 16, 2026

This test measures your body’s level of vitamin B12, a crucial nutrient for nerve function and red blood cell production. Low levels may indicate deficiencies or underlying health conditions.

Quick summary

["Vitamin B12 helps prevent nerve damage and anemia; low levels may need dietary adjustments or medical treatment."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
75685-8
Short code
Deprecated blaVIM Bld Pos Ql Prb Mag
Synonyms
Deprecated blaVIM Bld Pos Ql Prb Mag
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe-mag-capture
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Matters

Vitamin B12 is essential for maintaining healthy nerve cells and DNA synthesis. Your body absorbs it primarily from foods like meat, fish, and fortified foods. Deficiencies can develop slowly, especially in older adults or those with certain digestive disorders.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the draw if your blood is drawn in the morning. Wear a loose shirt for easy access.

What the Results Mean

Results help doctors diagnose conditions like pernicious anemia, vitamin B12 deficiency, or malabsorption issues. Low levels may prompt further testing or treatment recommendations.

Common Causes of Low Vitamin B12

Conditions like pernicious anemia (autoimmune disorder affecting stomach acid), celiac disease, or long-term vegan diets can reduce vitamin B12 absorption. Symptoms may include fatigue, numbness, or memory problems.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Vitamin B12 (Confirmatory)

Frequently asked questions

What might cause abnormal results?
Abnormal results could stem from dietary deficiencies, digestive disorders, or certain medications (e.g., proton pump inhibitors). Always discuss results with your healthcare provider for personalized guidance.
How often should I get this test?
Your doctor may recommend this test periodically if you have risk factors (e.g., older age, vegan diet, or history of digestive issues). Follow-up testing depends on your symptoms and lab results.
Can I take supplements before the test?
Yes, but avoid high-dose vitamin B12 supplements 24 hours before testing, as they may affect accuracy. Always follow your provider’s instructions.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy